 
   :expand        if true makes the canvas take the entire window
   :engine        can be :webgl :canvas or :auto (default :auto)
+  :default       true or false to set the default canvas to this
+                 created one. defaults to true.
 
   and either:
 

  "
  [opts]
  (let [{:keys [renderer canvas layer layers stage
                origins fullscreen-button] :or {origins {}} :as world}
        (into (make opts)
              (make-stage opts))]
    ;; add the stages to the canvas

  :y             y position for the new canvas
  :width         width of new canvas
  :height        height of new canvas"
  [{:keys [expand x y width height canvas engine background default]
    :or {expand false
         x 0
         y 0
         width 800
         height 600
         background 0x500000
         engine :auto
         default true}}]
  (let [fswidth (.-innerWidth js/window)
        fsheight (.-innerHeight js/window)

